Effects of arc oscillation on microstructure and mechanical properties of AZ31 magnesium alloy prepared by CMT wire-arc directed energy deposition

Cold metal transfer (CMT) arc with varied arc oscillation patterns was used to fabricate thin-wall AZ31 magnesium alloy components. The microstructure characteristics and mechanical properties of wire-arc directed energy deposition (DED) AZ31 magnesium alloy samples with or without arc oscillations were investigated experimentally. The samples were prepared by two oscillation modes, spiral oscillation and asymmetric trapezoidal oscillation, and compared with the samples without arc oscillation. Finer equiaxed grains were observed in the samples with arc oscillations and the stirring action of arc oscillation might result in the grain refinement. No visible anisotropy was found in microstructure and mechanical property in the AZ31 magnesium alloy samples with arc oscillations, and its mechanical characteristics were similar to the as-forged AZ31 alloy. As compared to the samples without arc oscillation, the yield strength and ultimate tensile strength of the arc oscillation sample increased from 70 to 90 MPa and from 196 to 233 MPa. In addition, the improvement mechanism of wire-arc DED components was discussed through the influence of arc oscillation on CMT wire-arc DED melt flow.